Management of Shoulder Deformities in Brachial Plexus Birth Palsies

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Background: During the last century, there has been growing evidence that dislocation of the glenohumeral joint in children commonly occurs with brachial plexus birth palsy, often in the first year of life. Etiology: Permanent injuries to the brachial plexus in childhood create a muscle imbalance about the shoulder during the reinnervation process. This results in an internal rotation contracture, external rotation weakness, and subsequent glenoid retroversion, posterior deficiency, joint subluxation, and eventual dislocation. Evaluation: On physical examination with scapular stabilization, there is limited passive external rotation in adduction and abduction. Ultrasounds, arthrograms, and magnetic resonance imaging help in evaluating the deformity of glenohumeral deformity and dislocation. At present magnetic resonance imaging is the standard on which operative intervention is based. Treatment: Initial treatment is physical therapy with passive glenohumeral mobilization with scapular stabilization. Failure to regain or maintain passive external rotation and evidence of joint instability or dislocation on examination are indicators for for futher evaluation and intervention. Nonsurgical interventions such as Botox injections, or splinting or SPICA cast may be considered. Ultimately, contracture release, potential joint reduction, and extra-articular muscle transfer surgery has been the standard of care, though there is ongoing debate regarding whether release alone is sufficient. It is important not to overlengthen the subscapularis or over release the glenohumeral joint, which can cause loss of internal rotation power and development of external rotation contracture. Outcomes: Early operative intervention in the form of extra-articular rebalancing techniques has become the standard of care, providing the best opportunity for enhanced motion and function, and improved validated Mallet, Active Movement, and Pediatric Outcomes Data Collection Instrument scores. Long-term improvements in outcome may rest on joint remodeling by arthroscopic or open reduction, though further research is still required to evaluate remodeling of joints over the course of a lifetime.